Method of manufacturing motor fuel



Feb- 8, 1949. L. c. KEMP, JR

METHOD OF MANUFACTURING MOTOR FUEL Filed oct. 2o, 1945 A Patented Feb. 8, 1949l Lebbeus C. Kemp, Jr., Scandale, N. Y., assigner to The Texas Company,

poration oi' Delaware New York, N. Y., a cor- Application October 20, 1945. Serial No. $273,475

' l This invention relates gasoline hydrocarbons of high octane rating.

The invention involves the catalytic conversion of synthesis gas, that is. a mixture of carbon monoxide and hydrogen, lunder suitable conditions of temperature and pressure into hydrocarvbons and hydrocarbon derivatives. The resulting hydrocarbons and hydrocarbon derivatives are converted into liquid hydrocarbons ofhighoctane rating by treatment with a cracking-catac lyst at elevated temperature as will be described.

The efliuent stream from a carbon monoxide hydrogenation reactor, operated to produce mainly hydrocarbons in the gasoline range, comprises gaseous hydrocarbons, liquid hydrocarbons, a small percentage of hydrocarbon: waxes and oxygenated hydrocarbons. carbon dioxide, steam and nitrogen. This effluent stream is cooled to effect condensation of steam and normally liquid hydrocarbons. Water and liquid hydrocarbons are separately removed,v leaving a residual gaseous fraction comprising carbonA dioxide, nitrogen, Ci up to about C hydrocarbons s and unreacted carbon monoxide and-hydrogen.

The substantially water-free liquid components, comprising hydrocarbons in the gasoline range,

` gas oil, higher boiling hydrocarbons, dissolved hydrocarbon waxes and oxygenated hydrocarbon derivatives are introduced into a catalytic cracking unit. The residual gaseous fraction is utilized to treat used catalyst from the aforesaid cracking reaction. This treatment is carried out under conditions so as to effect desorption and stripping of higher boiling hydrocarbons which are adsorbed on the cracking catalyst.

When employing a fluidized-catalyst cracking system, this stripping treatment is advantageously effected within the zone of vused catalyst removal from the cracking reactor. In suchvcase the stripping gas and hydrocarbons 'stripped from the catalyst pass on into the cracking reaction. l

Numerous advantages accrue `from using the gaseous components oi' the efiluent stream from the catalytic conversion ofcarbon monoxide and hydrogen forv stripping the adsorbed higher boiling hydrocarbons from a fiuidized cracking catalyst before its reactivation.

First, there is materially reduced the gradual deactivation of the cracking catalyst `which results from the conventional use of steamto-accomplish the stripping of adsorbed hydrocarbons from the catalyst in iluidized catalytic cracking operations. y

Secondly, the partial pressure of the liquid hyto a process for making 6 Claims. (Cl. Mii-449.6)

drocarbons in the fluid catalytic cracker is lowered substantially by the use of effluent gases from the hydrogenation of carbon monoxide to strip the adsorbed hydrocarbons from the catalyst since the'gases issue from the stripping section into the reactor of the cracking unit. The

reduction of the partial pressure of the hydrocarbons that are to be cracked results in decreased coke accumulation on the catalyst with consequent improvement i'n the eillciency of the cracking operation.

The invention can be better described and more fully understood by reference to the accompany` ing drawing wherein the method of flow of the whole operation is diagrammatically presented.

VMany other advantages and features of the invention will be apparent from the detailed de scription of the mode of operation which ensues.

vThe drawing shows only those operations which are/essential for a complete understanding of the process voi.' the invention; conventional heat exchangers and pumps are omitted in the interest of simplification.

Oxygen or an oxygen-rich gas, which is obtained from a source not shown, is introduced into a synthesis gasgenerator 5 through a feed pipe I. This gas ordinarily contains at least 50 molecular oxygen, but it is feasible to use air for the combustion. However, in most operations, the oxidizing gas used for preparing synthesis gas contains at least 50% molecular oxygen and preferably over molecular oxygen.

A hydrocarbon gas, preferably consisting mainly of methane, is introduced througha feed pipe 2 into the synthesis gas generator 5. In the diagram the oxygen-containing gas and the hydrocarbon gas are shown entering the generator 5 through separate feed lines in which there are usually inserted heaters which are not shown. The oxygen and hydrocarbon gas advantageously may be premixed before introduction into the synthesis gas generator 5 so -that the whole charge to the generator may be heated at once.

-In the synthesis gas generator 5, combustion occurs between oxygen and gaseous hydrocar- -bon to produce a mixture comprising mainly carv bon monoxide and hydrogen. This generator 5 may be of the furnace type which contains either refractory material so as to permit simple survantageously be employed to compress and liquefy air in the preparation of oxygen.

Carbon dioxide, which is obtained from a source which will be described in detail later, is also introduced into the synthesis gas generator 3. Thereby the temperature of the highly exothermic combustion of methane with oxygen. is tempered by the endothermic reaction of carbon dioxide with methane and means are provided for varying the molecular ratio oi' carbon monoxide to hydrogen in the synthesis gas.

The quantities of methane. oxygen and carbon dioxide introduced into the synthesis gas generator 5, are regulated so as to produce a synthesis gas containing carbon monoxide and hydrogen in the desired ratio. Usually a molecular ratio of carbon monoxide to hydrogen oi' 1:2 is the most advantageous. However, there are circumstances when molecular ratios oi' carbon monoxide to hydrogen varying from 1:1 to 1:3 are desired. In some cases it may be desirable or expedient to operate with carbon monoxide to hydrogen ratios even higher than 1:3.

It is possible to eii'ect tempering of the highly exothermic combustion of methane with oxygen by the introduction of steam into the synthesis gas generator E for steam also undergoes an endothermic reaction with methane. Moreover, the introduction of steam provides means of ad- Justing the carbon monoxide to hydrogen ratiov in the synthesis gas. The introduction of steam, as an alternative for or in conjunction with carbon dioxide, is not shown in the diagram, but such operation is included within the concept oi the invention.

pioyed determines the temperature at which the reactor I2 is maintained.

It a duidized system of catalytic conversion is employed, means such as a cyclone separator are provided to remove entrained dust from the emuent stream from the reactor I2.

` In the reactor I2, synthesis gas is converted into hydrocarbons by contact with the catalytic material contained therein and then issues from the reactor through the pipe 20. The eiliuent stream from the reactor contains unreacted carbon monoxide and hydrogen, diluent nitrogen. gaseous hydrocarbons. liquid hydrocarbons. carbon dioxide and steam, which latter two are byproducts of the catalytic conversion. The eiiiuent stream is cooled from the high temperature at which it issues from the reactor I2 in a heat exchanger 2I. In the heat exchanger 2I there is effected condensation of the steam and normally liquid constituents contained in the eiliuent from the reactor I2.

From the heat exchanger 2l, the effluent ilows along a pipe 22 into a gas-liquid separator 23. Therein the eilluent is separated into normally gaseous constituents and normally liquid ones. The water and normally liquid hydrocarbons leave the separator through a pipe 2l which leads to a decanter 25. The gaseous components ofthe eiiiuent issue from the separator 23 through a pipe 23. The disposal of these gaseous components will be described in detail later.

In the decanter 25, water is separated from the normally liquid hydrocarbons and is removed through an-exit pipe 21. The normally liquid hydrocarbons leavethe decanter 26 through a Synthesis gas, containing the desired molecular ratio of carbon monoxide to hydrogen, leaves the generator li through a pipe 8. The synthesis gas contains varying minor proportions of carbon dioxide and steam which maybe removed, if desil-ed, by conventional means, not shown, before' introduction of synthesis gas into the reactor suitable for the hydrogenationoi carbonmon-` oxide. Thus. steam can be removedv byconventional condensation while carbon dioxide 'can be removed by passage of the gases through'an absorber which contains a solution of an alkaline agent such as triethanolamine.

The synthesis gas is brought to the desired temperature in a heat exchanger, also not shown, v

before introduction through the pipe 3 into a carbon monoxide hydrogenation reactor I2. The

temperature at which the synthesis gas is introduced into the reactor |21 depends upon the catalyst and the type of operation that' is employed. For example, a xed bed operation employing a cobalt catalyst supported on a carrier I at atmospheric pressure operates most eiectively at a temperature of about 375 to 400 F. to produce liquid hydrocarbons in the gasoline range.

A iluidized catalyst operation employing an unsupported iron catalyst at about 200 to 250 pounds pressure operates most eiectively in the range of about 550 to 650 F. to produce liquid hydrocarbons in the gasoline range.

The reactor I2 can be of the fixed catalyst bed type or one of the various modications of uidized catalyst systems. l

An iron, cobalt, nickel, ruthenium or rhenium catalyst, either supported or unsupported, may

` be used in the reactor I2 to eilect the catalytic conversion oi synthesis gas into hydrocarbons. As indicated previously, the type of catalyst emreactor 38 of this iiuidized catalytic cracking unit,

the hydrocarbons contact a catalyst which is in the uidlzed state such as disclosed in U. S. Patent No. 2,361,978, for example. The numeral 31 desisnates the catalyst whose average particle size varies from `40 to 60 microns, depending upon the type of a fluid system that is employed.

The catalyst 31 may be of the synthetic type such as silica-alumina, alumina-burla, etc., or it may be of a natural type such as natural or acid activated clays of the bentonite type; moreover, it may be promoted or unpromoted. The type of catalyst employed will determine the operating conditions that will be maintained in the reactor 38. 'In general, atemperature between 850 to 1050? F. is maintained and the reactor may be designed to withstand operating pressures up to and above pounds per square inch.

By contact under the conditions outlined above. the hydrocarbon material, which has been introduced into the reactor 36 through the pipe 35 and which contains high boiling naphthas, gas oil, Diesel oil and other hydrocarbon material of low octane rating, are cracked to give a greater portion of hydrocarbons boiling in the gasoline range the catalyst. Therefore, a portion of the iluidized y catalyst is continuously removed from the reactor 36 for reactivation by removal of carbonaceous material in the regenerator section of the fluid catalytic cracking unit. i

Thus a portion of the uidized catalyst flows continuously over a baille 40 into a stripping section 4| in the lower portion of the reactor 36. Herein there is introduced all or a portion of the gaseous components of the'efiluent stream from the carbon monoxide hydrogenation reactor which which have been separated from the liquid components in the separator 23. As indicated previously, these gases leave the separator 23* through the pipe 26 and then may be diverted in whole or in part along a pipe 45 to a heater 46 in which they are raised to a temperature in the range of about- 300 to 500 F. The gases which comprise carbon dioxide, nitrogen, unreacted carbon monoxide and hydrogen and hydrocarbons which are mainly normally gaseous ones but some of which a'reof higher molecular weight up to about the Cios, leave the heater 46 through a pipe 4l and therethrough are introduced into the. stripping section 4| of the reactor 36.

The catalyst particles which enter the stripping section 4| contain a considerable amount of higher boiling hydrocarbons adsorbed on their surface and condensed in their capillaries and interstices. In conventional operation, steam is employed to strip these hydrocarbons from the catalyst. The cracking catalyst suffers gradual deactivation through the use of steam to eii'ect the removal of the adsorbed hydrocarbons from the catalyst. l

In the method of this invention, desorption of the higher boiling hydrocarbons from thecatalyst is effected by the introduction of the gaseous constituents of the eiliuent from the carbon monoxide hydrogenation reactor into the stripping section 4| at an elevated temperature. The use of these gases substantially `reduces the deactivation of the catalyst which results from the use of steam for this purpose and still emciently accomplishes the stripping of the hydrocarbons from the catalyst.

After the gases have effected the desorption of the higher boiling hydrocarbons from the catalyst, they pass around the baille 40 into the cracking section proper of the reactor 36. The pres ence of these gases in the reactor 36 reduces the partial pressure of the hydrocarbons that are cracked therein. This reduction in partial pressure of crackable hydrocarbons effects decreased coke formation on the catalyst thereby increasing the efficiency of the cracking operation.

The products of the catalytic cracking and the gases which have been used to effect the desorption of the hydrocarbons from the cracking catalyst prior to its reactivation issue from the cracking reactor 36 through a pipe `48. Batlles 38 remove entrained catalytic material from thel gaseous stream before it issues from the reactor 36. Cyclone separators may be used instead of the bales 38 to eiiect the removal of the entrained catalytic particles from the gaseous stream. The treatment of the eilluent which leaves the reactor 36 through the pipe 48 will be described more in detail later.

After the catalyst has been stripped of adsorbed hydrocarbons in the stripping section 4| of the reactor 36 through the action of the gaseous con- 6 stitutents `o1' the ellluent from the hydrogenation of carbon monoxide, it is continuously withdrawn from the reactor 36 through the conduit 50, and flows vtherethrough into the pipe 5|. AAir or oxygen, which is obtained from a, source not shown, is pumped under'pressure through the pipe 5|, thereby providing means for transporting the catalyst from the reactor 36 to the regenerator 52 A through the pipe 5|. In the regenerator 52, the catalyst is reactivated by removal of the accumulated coke by combustion with the air orioxygen which has been introduced therein in the manner just described. `lAir is ordinarily used toeii'ect this combustion. It is desirable to keep the combustion temperature in the regenerator 52 in the range of 1,000 to 1,200 F. soas to avoid deactivation of the catalyst.

The numeral 31 lalso designates the catalytic material which is undergoing reactivation by removal of the coke in the regenerator 52. Cyclone separators plus electrical precipitators or similar devices, not shown, are provided to remove entrained catalyst from the ellluent from the regenerator 52. This effluent comprises .mainlyv carbon dioxide, carbon monoxide, nitrogen and oxygen which has not been utilized in the combustion. The treatment of this eliluent stream Will be described in detail later.

. A portion of the reactivated catalyst'continuously iiows over a baie'56 into the lower portion of the regenerator 52 whence it is continuously returned to the reactor 36. The reactivated catg alyst leaves the regenerator '52 through a conduit 51 which flows into the feed line 35 through which the hydrocarbons that are to be cracked are introduced into the reactor 36. The flow of these hydrocarbons along the pipe 35 provides means of returning the reactivated catalyst to the reactor 36. The catalyst, at an elevated temperature because of the combustion, imparts its heat to the stream of hydrocarbons that are introduced into the reactor 36 through the pipe 35.

The ellluent from the reactor 36, comprising the products of the cracking operation and the gases which were used to eiect the stripping of the absorbed hydrocarbons, pass along the pipe 48 to a fractionator 60. Herein the higher boiling hydrocarbons, such as gas oil, which have not been converted into gasoline hydrocarbons in the crackin-g operation, are condensed and thereafter are' recycled through the pipe' 6| to the reactor 36 for further treatment, or led to storage through the pipe 63. 'I'he pipe 6| leads into the feed line 35 whence the recycle gas oil is returned to the reactor 36. The recycle gas oil is `raised to cracking temperature by-.contact with the hot regenerated catalyst which flows through the conduit 51 into thefeed line 35.

The lower boiling hydrocarbons, comprising gasoline and the normally gaseous components of the eflluent from the reactor 36, leave the fractionator 60 through a pipe 64 and therethrough are introduced into a stabilizer 65. Herein the gaseous components of the eiiluent from the cracking operation, such as carbon dioxide, hydrogen, carbon monoxide, nitrogen,`and C1 to C4 hydrocarbons, are separated from the gasoline fraction. The gasoline fraction is removed through the pipe 66 and is piped to storage, not shown.

The .portion of the gaseous eiliuent from the hydrogenation of carbon monoxide which is not used for stripping the adsorbed hydrocarbons from the cracking catalyst in the stripping zone 4| prior to its reactivation, passes along a pipe B2 which connects with the pipe 28 through which the gaseous eiiiuent leaves the separator 23. Through the pipe 62, this portion of the gaseous effluent from the hydrogenation of carbon monoxide enters the stabilizer 65, wherein any gasoline hydrocarbons contained therein are separated. The gasoline separated therefrom merges with the gasoline resulting from the cracking operation and is removed from the stabilizer through the pipe 66. The gaseous components. comprising carbon dioxide, nitrogen, unreacted carbon monoxide and hydrogen and C1 to C4 hydrocarbons, combine with the gaseous traction of the eiiluent from the cracking reactor 38.

The combined gaseous fractions, comprising the components enumerated above, leave the stabilizer 65 through a pipe 61 and pass therealong to a hydrocarbon absorption unit 88 which is of the conventional type adapted to eil'ect ab- \s orption of hydrocarbon gases. The C1 to C4 hydrocarbons and some methane are absorbed in the absorption unit 6B wherein an absorbing medium, such as charcoal or gas oil, is employed. The hydrocarbons which are absorbed in the absorbing medium are stripped from the absorbent in a separate section of the absorption unit 88 and are removed therefrom through a pipe 19 whence they are piped to storage, not shown.

The gas which leaves the hydrocarbon absorption unit 6B through a pipe 1D comprises carbon dioxide, nitrogen, hydrogen, carbon monoxide and methane. This gas is advantageously returned at least in part to the synthesis gas generator wherein its content of methane and carhon dixoide may be utilized in the preparation oi' synthesis gas. The hydrogen and carbon monoxide present in this gaseous fraction may serve as diluents to moderate the highly exothermic oxidation taking piace in the synthesis gas generator 5. A portion of the gas must first be vented, however, to prevent an accumulation of nitrogen in the system. This may be accomplished through the vent 1i. The unvented portion of this tail gas proceeds along the pipe I0 until it is introduced into the hydrocarbon feed line 2 whence it is introduced into the generator i. f

Alternatively or simultaneously a portion of this gas comprising carbon'monoxide, hydrogen. carbon dioxide, methane and nitrogen may be introduced into the synthesis reactor i2 through a' pipe 12 which leads from the pipe 'I0 to the feed pipe 6.

The eilluent from the regenerator l2 contains mostly carbon dioxide, carbon monoxide, nitrogen and oxygen which has not been utilized in ,the combustion. This eiiluent passes along the pipe 54 to a carbon dioxide absorbing tower 15. Therein the carbon dioxide portion of this enluent is absorbed in a suitable medium, such as a solution of triethanolamine. The unabsorbed comline for the oxidizing gas I, .and therethrough carbon dioxide is introduced into the synthesis gas generator 5.

' Alternately the carbon dioxide may be introduced into the synthesis reactor i2. This may be effected by passing the carbon dioxide along a pipe 82 which leads from the pipe 80 to the pipe y 8 which is the feed line to the reactor i2. Through the pipe B the carbon dioxide is introduced into the reactor l2 together with the synthesis gas.

While mention is specically made of the use of methane for the preparation of the synthesis gas, other hydrocarbon gases may be utilized in the preparation of synthesis gas. As a matter oi fact, synthesis gas from any source may be used.

An additional advantage of the use of the coniunctive operation resides in the fact that in the cracking operation, the oxygenated products present in the .products of the hydrocarbon synthesis are deoxygenated. The olens so formed thelundergo a double bond shift type of isomer- .ization The deoxygenation and isomerization result in improved products.

In the description oi the invention, the hydrogenation of carbon monoxide is described as em- "ployed in conjunction with a iiuidized system oi ponents of the gas stream are vented through the vent 16. The absorbing medium is continuously passed to a carbon dioxide-stripping section 11 through a pipe 18. In the stripping section 11, the carbon dioxide is stripped from the absorbing medium and exits from the stripping section 11 through a pipe 80. The regenerated absorbing medium returns to the absorbing section 15 through a pipe 19.

The carbon dioxide passes along the pipe B0 to a vent 8l through which it may be vented in whole or in part. Advantageously, a portion of this carbon dioxide is returned to the synthesis gas generator 5, wherein it is utilized in the preparation 0f Synthesis 88S- The Pipe 80 leads to the feed 75 said usedcatalyst prior to said combustion to concatalytic cracking. However, the invention contemplates the use of a carbon monoxide hydrogenation process in conjunction with any type of catalytic cracking operation. wherein a portion of the catalyst is continuously regenerated, and wherein stripping of the adsorbed hydrocarbons prior to regeneration is necessary in order to avoid the loss ot a considerable portion oi hydrocarbons in the combustion which takes place in the regenerator zone.

In accordance with the invention, the hydrogenation of carbon monoxide can be employed in conjunction with a hydroforming operation. The hydrogen resulting from the hydroforming process may be used to supplement the synthesis gas in which there is sometimes a deciency of hydrogen depending on the source of the synthesis gas.

Obviously, many modiilcations and variations of the invention, as hereinbefore set forth, maybe made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the4 appended claims.

I claim:

l. In a catalytic conversion of a mixture of carbon monoxide and hydrogen into liquid hydrocarbons of high octane rating, the steps which comprise preparing synthesis gas comprising hydrogen and carbon monoxide in a gas generation zone by the oxidation of carbonaceous material, converting saidsynthesis gas intov hydrocarbons and hydrocarbon derivatives by contact with a synthesis catalyst under conversion conditions of temperature and pressure, separating the reaction products into a normally liquid fraction and a normally gaseous fraction, continuously passing the liquid fraction in contact with a mass of finely divided, catalyst maintained at a temperature eilective for catalytically cracking hydrocarbons, continuously discharging products of cracking from the cracking zone, continuously removing from the cracking zone used catalyst, subjecting removed catalyst to contact with an oxidizing gas in a zone of reactivation to effect combustion of carbonaceous -material contained in the catalyst, thereby forming a ilue gas containing carbon dioxide, separating carbon dioxide from said flue gas, subjecting solid, hydrocarbon-conversionl tact with a stripping gas comprising a portion at least of the gaseous eiiluent ,-fom the catalytic conversion of carbon monoxide and hydrogen, in a stripping zone under conditions effective to strip adsorbed hydrocarbons from said catalyst, passing said stripping gas and resulting desorbed hydrocarbons from the stripping zone to said cracking zone, subjecting the combined products, from the cracking zone to a separation process ei'iective l least of the said carbon dioxide separated from said ue gas, to the synthesis gas subjected to contact with said synthesis catalyst.

2. In the catalytic conversion of -a mixture of carbon monoxide and hydrogen into liquid hydrocarbons of high octane rating, the steps which comprise preparing synthesis gas comprising hydrogen and carbon monoxide in a gas generation zone by the oxidation of carbonaceous material, converting said synthesis gas into hydrocarbons and hydrocarbon derivatives by contact with a synthesis catalyst under conversion conditions of temperature and pressure, separating the reaction products into a normally liquidfraction and a normally gaseous'fraction, continuously passing the liquid fraction in contact with a mass of` nely divided, solid, hydrocarbon-conversion catalyst maintained at a temperature eiective for catalytically cracking hydrocarbons, continuously removing from the cracking zone used catalyst, subjecting removed catalyst to contact with an oxidizing gas in a zone of reactivation to eiiect combustion of carbonaceous material lo carbons in high octane. rating wherein a carbonaceous material is submitted to partial combustion in a synthesis gas generation zone in the presence of molecular oxygen under exothermic conditions for the production of a synthesis gas comprising hydrogen and carbon monoxide, the synthesis gas being converted into hydrocarbons and hydrocarbon derivatives in va reaction zone by contact with a hydrocarbon synthesis catalyst under conversion conditions of temperature and pressure, the reaction products separated into -a normally liquid fraction and a normally.

gaseous fraction, and a normally liquid fraction is continuously passed in contact with-a mass of fixlly divided, solid particle, hydrocarbon-conve ion catalyst maintained at a temperature eiective for catalytically cracking said normally liquid fraction, the improvement which comprises continuously removing used catalyst from the cracking zone, subjecting said removed catalyst to contact with an oxidizing gas to eiect combustion of carbonaceous material deposited on the catalyst, thereby 'forming a flue gas containing carbon dioxide, separating carbon dioxideirom said ilue gas, subjecting said used catalyst prior to combustion to contactwith stripping gas comprising a portion at least of the said normally gaseous fraction derived from the catalytic reaction of carbon monoxide and hydrogen, in a stripping zone under conditions effective to strip adsorbed hydrocarbons from the catalyst, passing the said stripping gas and resulting desorbed hydrocarbons from the stripcontained in the catalyst, thereby forming a flue gas containing carbon dioxide, separating carbon dioxide from said flue gas, subjecting said used ping zone to said cracking zone, recovering normally liquid hydrocarbons from the combined products of the cracking zone, thereby leaving a normally gaseous streamof products from the cracking zone, venting a portion-of said normally gaseous stream, separatingithe remainder into at least two streams, continuously conveying one of said streams of gas into admixture with the synthesis catalyst, and continuously directing the other stream into said synthesis gas generation zone for the production of additional synthesis gas, simultaneously conducting said carbon dioxide separated from said ue gas into admixture with the synthesis catalyst.

cover normally liquid hydrocarbons and delivering a stream of normally gaseous products, re-

cycling a portion of said last-named stream together with a portion at least of the said carbon dioxide separated from said ue gas to said synthesis gas generation zone for formation of additional synthesis gas,` including said additional synthesis gas in the mixture converted to hydrocarbons and hydrocarbon derivatives, as aforesaid, and continuously admixing a second portion of said normally gaseous product stream and an additional portion of carbon dioxide separated' from said flue gas, with the synthesis gas subliected to contact with the synthesis catalyst for the preparation of hydrocarbons and hydrocarbon derivatives.

3. In the catalytic synthesis of liquid hydro- 4. In thecatalytic conversion of a mixture of carbon monoxldeand hydrogen into liquid hydrocarbons of high octane rating, the steps which comprise preparing synthesis gas compris ing hydrogen and carbon monoxide in a gas generation zone by the oxidation of carbonaceous material, converting said synthesis gas into hydrocarbons and hydrocarbon derivatives by contact with a synthesis catalyst under conversion, conditions of temperature and pressure, separating the reaction products into a normally liquid fraction and a normally gaseous fraction, continuously passing the liquid fraction in contact with a mass of nely divided solid, hydrocarbon-conversion catalyst maintained at a temperature effective for catalytically cracking hydrocarbons,. continuously discharging products of. cracking from the cracking zone, continuously removing from the cracking zone used catalyst, subjecting removed catalyst to contact with an oxidizing gas in a zone of reactivation to effect combustion of carbonaceous material contained in the catalyst, thereby forming a flue gas containing carbon dioxide, separating carbon dioxide from said ue gas, subjecting said used catalyst prior to said combustion to contact with a stripping gas comprising a portion at least of the gaseous eiliuent from the catalytic conversion of carbon monoxide and hydrogen, in a stripping zone under conditions eiective to strip adsorbed hydrocarbons from said catalyst, passing said stripping gas and resulting desorbed hydrocarbons from the stripping zone to said cracking zone, subjecting the combined products from the cracking zone to a separation process eiective to recover normally liquid hydrocarbon products of reaction and deliver a normally gaseous stream containing the normaily gaseous products from said cracking zone, and continuously supplying a substantial portion at least of said normally gaseous stream together with a portion at least of said carbon dioxide separated from said tlue gas to the synthesis gas subjected to contact with said synthesis catalyst for the preparation of hydrocarbon and hydrocarbon derivatives.

5. The method according to claim l wherein said oxidation of said carbonaceous material in the gas generation zone comprises partial combustionof said carbonaceous material in the presence of free oxygen under exothermic conditions.

6. The method according to claim 4 wherein said oxidation of said carbonaceous material in the gas generation zone comprises partial comburstion of said carbonaceous material in the presence of tree oxygen under exothermic conditio'nsl LEBBEUS C. KEMP, Ja.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

